Shizuoka Public High School Entrance Examination - Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Average velocity

Displacement divided by the time taken, including direction. A round trip has zero average velocity even though the distance travelled and average speed are nonzero.

Newton's second law

Net force equals mass times acceleration (F = ma). For a fixed mass, doubling the net force doubles acceleration; for a fixed force, doubling mass halves acceleration.

Conservation of mechanical energy

When friction is ignored, the sum of kinetic and gravitational potential energy stays constant. A falling ball converts mgh into ½mv², so its speed depends only on height dropped.

Pressure in solids

Pressure equals force divided by contact area, measured in pascals. The same force gives more pressure through a smaller area, as with a sharp knife edge.

Ohm's law

Voltage equals resistance times current (V = RI). For a fixed resistor, current is proportional to voltage; a filament lamp's resistance rises as it heats.

Parallel circuit rules

Voltage is equal across every branch, branch currents add to the total, and total resistance is smaller than any single branch resistance.

Electric power

Power equals voltage times current (P = VI), also written I²R or V²/R, in watts. Energy used is power times time, and one kilowatt-hour equals 3.6 million joules.

Electromagnetic induction

Moving a magnet into or out of a coil induces a voltage; the induced current creates a field opposing the change. This principle underlies generators and transformers.

Wave speed relation

Wave speed equals frequency times wavelength (v = fλ). When a wave crosses into a new medium, frequency stays fixed while speed and wavelength change.

Refraction toward the normal

Light entering a denser medium such as glass from air slows and bends toward the normal; leaving, it speeds up and bends away. This makes a straw look bent in water.

Convex lens images

An object beyond twice the focal length gives a real, inverted, diminished image; between one and two focal lengths, a real, inverted, magnified image; inside the focal length, a virtual, upright, magnified image.

Sound needs a medium

Sound is a longitudinal wave of compressions and rarefactions. It travels about 340 m/s in air, faster in water and solids, and cannot cross a vacuum.

Distillation

A separation method that boils a liquid and condenses the vapour. It separates a solvent from dissolved solids or two liquids whose boiling points differ enough.

Diffusion

The spontaneous spreading of particles from high to low concentration caused by random motion. It is fastest in gases and slows as temperature falls.

Chemical versus physical change

A chemical change forms a new substance with different properties and is usually hard to reverse; a physical change alters state or form only, such as melting or dissolving.

Chromatography

A separation technique in which dissolved substances move up paper or a plate at different rates because of differing solubility and adsorption, revealing coloured components.

Balancing equations

Atoms are conserved in a reaction, so coefficients are adjusted until each element's atom count is equal on both sides. Subscripts within formulas are never changed.

Oxidation and reduction

Oxidation is loss of electrons or gain of oxygen; reduction is the reverse. In a reaction such as copper oxide with carbon, the two always occur together.

Reactivity series

A ranking of metals from potassium, sodium, calcium, magnesium, aluminium, zinc, iron, copper, silver to gold. A more reactive metal displaces a less reactive one from solution.

Combustion products

Burning a hydrocarbon in plenty of oxygen gives carbon dioxide and water. Limited oxygen also produces carbon monoxide, a poisonous gas that binds haemoglobin.

Neutralisation

An acid reacts with a base to form a salt and water. In ionic terms, hydrogen ions and hydroxide ions combine to form water, and the reaction releases heat.

pH scale

A measure of hydrogen ion concentration: below 7 acidic, 7 neutral, above 7 basic. Each one-unit change means a tenfold change in hydrogen ion concentration.

Acid plus carbonate

An acid reacting with a metal carbonate produces a salt, water, and carbon dioxide gas. The gas turns limewater milky, which is the standard test for it.

Mitosis versus meiosis

Mitosis makes two identical diploid cells for growth and repair. Meiosis makes four genetically varied haploid gametes, halving the chromosome number before fertilisation restores it.

Dominant and recessive alleles

A dominant allele is expressed even when only one copy is present; a recessive allele shows only when both copies are recessive. A cross of two heterozygotes gives a 3:1 phenotype ratio.

Villi

Finger-like projections of the small intestine wall that greatly increase surface area for absorbing digested nutrients. Their thin walls and dense blood vessels speed transfer into the blood.

Homeostasis

The maintenance of stable internal conditions such as temperature and blood glucose. Insulin lowers glucose, sweating and vasodilation cool the body, and shivering warms it.

Energy flow in food chains

Producers capture light energy, and only about ten percent passes to each higher trophic level because energy is lost as heat and in waste. Chains are therefore short.

Eutrophication

Nutrient runoff triggers algal blooms; the algae die and decomposers consume oxygen, so fish and other animals suffocate. It is a major form of water pollution.

Principle of superposition

In undisturbed sedimentary strata, lower layers are older than upper ones. A fault or intrusion cutting across layers is younger than the layers it cuts.

P-waves and S-waves

P-waves are fast longitudinal waves that pass through solids and liquids; S-waves are slower transverse waves that cannot pass through liquids. Their arrival gap locates an epicentre.

Moon phases

The Moon's appearance depends on the Sun–Earth–Moon angle: new moon lies between Earth and Sun, full moon is opposite. The cycle repeats about every 29.5 days.